3-Amino-2-arylpropanoic acids by electrophilic substitution of 2-arylethylamines at the benzylic position

Title amino acids I (R, R1, R2 = H, OMe) were prepd. from 2-arylethylamines II by a reaction sequence consisting of N-pivaloylation, lithiation at the benzylic position with tert-BuLi, carboxylation, and deprotection by refluxing in 20% hydrochloric acid. [on SciFinder (R)]